1. Field
The present invention relates to an apparatus and method for power management and control in portable electronic equipment, and more particularly, to an apparatus and method for power management and control of a battery pack or a fuel cell pack for generating a voltage when the fuel cell pack is connected to portable electronic equipment having an operation block driven by a driving voltage of the battery pack.
2. Description of Related Art
With the recent development of electrical and electronic communication and electrochemistry-related industries, portable electronic equipment such as laptop computers, and personal digital assistants (PDAs) is typically driven by a voltage of a battery. For this reason, there have been conducted researches on a longer life span of a battery. Of course, when the equipment is provided with an AC-adaptor that converts commercial power (AC power) into a DC voltage, the equipment does not require such a battery at places where the commercial power is available.
However, because a primary object of portable electronic equipment is to allow a user to use the equipment during movement, it is required to drive an operation block of portable electronic equipment by means of a voltage of a battery during a longer period of time at outdoor places where commercial power is not available. To this end, portable electronic equipment contains a power management and control apparatus for efficiently managing the power of a battery.
Further, various power supplies have been developed to extend a use time of portable electronic equipment such as notebook computers. As a typical example, there is a fuel cell that generates electricity through the supply of fuel and outputs a voltage. As known in the art, the fuel cell generates a voltage in an electricity-generating body by supplying fuel such as hydrogen or methanol and air as an oxidizer gas to a stack so that the fuel and the air can electrochemically react with each other. A fuel cell pack includes a DC-DC converter for adjusting the output of power (voltage) generated by a fuel cell, and a fuel cell controller for controlling the output of the DC-DC converter according to an external demand.
An example in which such a fuel cell and a rechargeable battery are integrated into a hybrid pack to be used as a driving power source for portable electronic equipment is disclosed in International Publication No. WO 2005/003941 published on Jan. 13, 2005, entitled “Electronic Equipment, Power Source Management Control Device For Electronic Equipment, And Power Source Device” and filed on Jun. 30, 2004 in the name of Sony Corporation (hereinafter, referred to as “the WO 2005/003941 system”).
In the WO 2005/003941 system, the device comprises a battery as a secondary battery, a battery protecting circuit for controlling the battery, a fuel cell for generating power in an electricity-generating body by causing fuel and air to electrochemically react with each other, and a fuel cell controller for controlling the fuel cell.
The fuel cell controller and the battery protecting circuit transmit and receive information on a charged remaining capacity of the battery and the state of an output voltage of the fuel cell via a system management bus.
In the WO 2005/003941 system, the fuel cell controller and the battery protecting circuit share system load information of a central processing unit (CPU), which is recognized by an operating system (OS), in a computer via the system management bus so as to properly control the outputs of the fuel cell and the battery according to the load information.
For example, if portable electronic equipment can be sufficiently driven only by the output of the fuel cell, the battery is charged using the output of the fuel cell. If the portable electronic equipment cannot be driven only by the output of the fuel cell, the voltage of the battery is further discharged and supplied. If the fuel cell and the battery cannot supply power required by the portable electronic equipment, a main body of the computer is forcibly shut down.
However, in the WO 2005/003941 system, the fuel cell controller acquires the amount of power required by the portable electronic equipment, i.e., load information of a central processing unit (CPU), which is recognized by OS, via a system bus to recognize desired system power and then recognizes the desired amount of power, i.e., consuming power information, based on task scheduling. That is, it is impossible to perform power management and control corresponding to an actual system load.
Further, in the WO 2005/003941 system, if consuming power required at the system load exceeds the output power of the fuel cell and the charged remaining capacity of the battery, the main body of the computer is shut down. Accordingly, a smooth operation of the system cannot be attained.
Typically, in portable electronic equipment such as a portable computer, much power is consumed suddenly when several tasks are simultaneously processed by an optical disk driver (ODD), a floppy disk driver (FDD), and the like. Even though this situation does not frequently occur and occurs only during a short period of time, a main body of a computer system is forcibly shut down. Accordingly, this causes user's inconvenience in using the portable electronic equipment.